This invention relates to systems for multiple completions where more than one producing zone is traversed by a well bore and production can be obtained from more than one production zone into a common string of tubing. More particularly, this invention has to do with a system for monitoring the quantity of production from independent production zones by independently measuring the differential pressure and the static pressure in a production zone on a real time basis while providing a full opening bore for production and remedial operations of lower zones.
Heretofore, there has been a problem with multiple completions in that regulatory agencies can require the operator to produce from only one single production zone at a time in a multiple zone well so that the production quantity for each zone can be independently ascertained. While this occurs, the other production zones cannot be produced and are, in fact, shut off. In multilateral completions (earth surface or underwater), it is also common to connect lateral pipes in a given production zone to a zone of production so that multiple zone productions are obtained and it is of vital interest to monitor the production flow from each zone.
The system heretofore principally utilized uses multiple packers in a well casing where the packers separate production zones. A string of production tubing extends through the well packers and a side pocket mandrel is located in a section of the tubing string between a pair of production packers. The side pocket mandrel is utilized in the control of fluid flow which enters the tubing string through the bottom of the side pocket mandrel. One method of control is simply to block the passage so that fluid flow is stopped and fluid is produced from a selected side pocket and the fluid flow is measured at the earth""s surface. In any event, it is not possible to ascertain what fluid flow occurs with any degree of preciseness and production is typically limited to one zone at a time.
In the present invention, in a multiple completed well, spaced apart production packers are provided to isolate independent production zones from one another. In each of the isolated production zones, a side pocket mandrel is provided with a full opening bore, i.e. a bore which does not restrict the passage of well tools. The side pocket mandrel has lengthwise extending side by side elongated pockets (1) for receiving a static pressure measuring instrument or tool (static pressure pocket); (2) for providing an elongated pressure differential flow passageway (flow passageway pocket); and (3) for receiving a differential pressure measuring tool (differential pressure pocket). The static pressure measuring tool and the differential pressure measuring tool or instrument are commonly connected by a data coupling means to a single electrical conductor line which is strapped to the string of tubing and extends to the earth""s surface for transmission of control signals and data between the earth""s surface and the various side pocket tools. The differential flow passageway is connected for fluid communication with the static pressure pocket and the differential pressure pocket in the side pocket mandrel. Fluid flow in the production zone is channelled through the flow passageway to the full opening bore and the fluid is communicated to the static pressure measuring tool and to the differential pressure tool. The flow passageway is constructed and arranged to develop a differential pressure which is measured by the differential pressure measuring tool and which can be stored in a memory of the tool. At the same time, the static pressure of the production fluid in the production zone is measured by the static pressure measuring tool. Both the differential pressure measurements and the static pressure measurements can be recorded in a memory as a function of real time.
When a electrical polling signal is generated at the earth""s surface to a specific side pocket mandrel, the static pressure and the differential pressure of the production fluid are read out at the surface as real time data by transmission to the earth""s surface on the conductor cable.
A real time reference can also be generated in the well tools and initiated when the tools are installed for use with a memory. With retrievable tools, both the static pressure tool and the differential pressure tool can be independently retrieved at any time and the memories can then be read out independently at the earth""s surface should the conductor line fail to function for one reason or another.
With the present system, the static pressure and differential pressure of fluid flow from each production zone is independently measured at the time of production and sequentially and repetitively read out at the earth""s surface. From the pressure measurements and flow equations, the production flow is determined. With the equipment arrangement, a full bore opening is also provided so that any remedial operations or the like can be conducted on lower zones without requiring removal of any other devices in full opening bore.